The use of computer implemented models to evaluate complicated systems has become increasingly popular. A well-designed, adequately validated model can be used to understand current conditions and predict future trends. The ability to accurately model multi-variable systems can aid in optimizing current resources and allow for future planning.
One area in which computer models have become increasingly important is in the area of vehicle traffic control and road maintenance. The continued increase in population means that the number of vehicles traversing the roadways has also increased and will continue to increase. As a result, it has become more important for large and small municipalities to be able to improve traffic safety and determine how limited resources for road construction and maintenance can be optimally allocated in their areas. Software modeling applications for simulating traffic and road conditions are becoming more commonly used as a tool for analyzing traffic operations.
This increase in their importance has led to computer programs for traffic simulation becoming increasingly more advanced and sophisticated over the past two decades. Usage of traffic simulation has increased significantly; and this high-fidelity modeling, along with moving vehicle animation, has allowed important transportation decisions to be made with better confidence. During this time, traffic engineers have typically been encouraged to embrace the process of calibration, in which steps are taken to reconcile simulated and field-observed traffic performance.
According to international surveys, top experts, and conventional wisdom, existing (non-automated) methods of calibration have been difficult and/or inadequate. Consulting engineers and DOT personnel have expressed strong interest in making calibration faster, cheaper, easier, and requiring less engineering expertise. Some users of simulations have been unwilling to perform any amount of calibration; frequently citing labor-intensive data collection procedures, or a lack of coherent procedures and guidelines. Some simulation users have also tried to apply procedures and guidelines that exist in the literature; but have found that these guidelines are difficult to apply, or that the guidelines are a poor fit for their specific type of simulation analysis. Finally, some simulation users believe that they have somewhat mastered the process of calibration; but that the amount of engineering expertise required to achieve this mastery could be measured in decades, or that successful execution of calibration for a new project could require many weeks of hard work.
There has been a significant amount of research in the area of automated calibration techniques, for traffic simulation. However, many of these research projects and papers have not provided the level of flexibility and practicality that are typically required by real-world engineers. There is a need for a calibration method that can increase the effectiveness of computer models. Such a calibration method will ideally be simple to implement, provide sufficient customization to accommodate different user needs, and increase the efficiency of computer models.